Appearance

Cyperus rotundus is a perennial which rarely reproduces by seed but extensively reproduces by rhizomes which initially are white and fleshy with scale leaves, later becoming ligneous or "wiry."

Foliage

The leaves are three-ranked, shiny, dark green, and corrugated in cross section. They are 0.24-0.39 in. (6-10 mm) wide and 3.9-13.8 in. (10-35 cm) long. The rachis, which grows through the center of the leaf bundle, is erect, simple, smooth, triangular in cross section, and 3.9-23.6 in. (10-60 cm) long.

Flowers

Near the ends are clusters of narrow spikelets, 0.3-1 in. (0.8-2.5 cm) long and 0.07 in. (2 mm) wide, 10- to 40-flowered, acute and compressed with a red, reddish-brown, or purplish-brown color.

Fruit

Fruits are 3 angled achene.

Ecological Threat

Infests crop production areas in tropical and temperate climates, causing large losses in crop yields.

Selected Images

Maps

Invasive Listing Sources

• California Noxious Weeds
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• WeedUS - Database of Plants Invading Natural Areas in the United States

References